The present invention relates to a position control device of the type which may be used, for example, to control the movement of a cursor of a video display, as in a video game.
The invention relates in particular to position control devices for controlling position along a single axis. Such position control means is disclosed, for example, in U.S. Pat. No. 4,195,938, and includes a rotary encoder which generates position control signals in response to rotation of a shaft, the control signals indicating the speed and direction of the shaft rotation for effecting corresponding movements, such as movements of a video display cursor, along a single axis.
Devices for effecting such position control along two orthogonally related axes are commonly referred to as trackball devices, one such trackball device being disclosed, for example, in my copending application Ser. No. 347,469, filed Feb. 10, 1982 and entitled "TRACKBALL DEVICE". The trackball device includes a ball loosely seated on supports in a housing for universal rotation of the ball, a portion of the ball projecting through an opening in the housing for access by a user so that the user can manually rotate the ball.
Both trackball devices and single-axis position control devices have, heretofore, been characterized by single manual control members which limits the configurations in which the device can be mounted and correspondingly limits the applications of the device.
Furthermore, in prior position control devices, the axis of rotation of the shaft is fixed, and proper operation of the device requires manufacture of the parts to very exacting tolerances. This is quite costly, since it precludes the use of certain inexpensive materials and fabrication techniques. Additionally, such prior devices have tended to be unduly rattly and have exhibited poor shock and impact resistance.